Lemma 4 can be used in an alternating minimization method to find the CP decomposition with the given signature. An update of \({\bf A}\)  given the matrices \({\bf B}\)  and \({\bf C}\) , and an update of \({\bf B}\)  given \({\bf A}\)  and \({\bf C}\)  would be obtained from (REF ) by cyclic change \({\bf A}\rightarrow {\bf B}\rightarrow {\bf C}\rightarrow {\bf A}\) . However, like in the ordinary ALS, the convergence might be slow and diverging solutions may be obtained, in which norms of the factor matrices go to infinity. More sophisticated algorithms exist [1]}, [2]}.
